Hydraulically balanced stepwise variable displacement vane pump

ABSTRACT

A binary vane pump providing a balanced, stepwise variable displacement is provided. The binary vane pump includes a pressure plate having first and second discharge ports configured to discharge fluid from the binary vane pump to a first discharge path and a thrust plate having third and fourth discharge ports configured to discharge fluid from the binary vane pump to a second discharge path. The binary vane pump also includes a ring positioned axially between the pressure plate and thrust plate, the ring having an inner cam surface, a rotor rotatably disposed within the ring, the rotor having a plurality of slots and a plurality of vanes received and movable within respective slots, and a shaft extending along an axis through the rotor and configured to rotate the rotor so that the vanes are rotatable within the ring.

BACKGROUND OF THE INVENTION

The following description relates to a vane pump, and in particular, a hydraulically balanced, stepwise variable displacement binary vane pump.

A conventional vane pump may include a thrust plate, a ring, a rotor having vanes connected thereto, a pressure plate and a drive shaft. The vane pump may be configured as a balanced cartridge design having two pumping chambers. Each pumping chamber includes an intake port and a discharge port. The respective intake ports and discharge ports are symmetrically arranged. Due at least in part to this arrangement, forces generated at one side of the pump are counteracted by the other side.

In the conventional vane pump, two pumping chambers formed in the ring are connected to a common output circuit. That is, the two pumping chambers discharge fluid to a common circuit via respective discharge ports. As a result, the pumping chambers both push against a common resistance in the common circuit, thereby providing a high flow rate even when a high flow rate may not be necessary. The common resistance on the two pumping chambers requires more mechanical torque/power to drive the pump.

A binary vane pump having a variable displacement has been proposed. In such a pump, two pump chambers have a respective discharge port. Each discharge port flows to a different flow path. Flow output may be controlled by closing a valve to restrict flow from one of the discharge ports. However, this configuration may result in an unbalanced load when the load applied is different for each pumping chamber. The unbalanced load may lead to excess noise and/or wear on the parts of the pump, which may reduce the service life of the pump.

Accordingly, it is desirable to provide a binary vane pump that separates the two pumping chambers in a balanced arrangement and allows for stepwise variable displacement. In such a configuration, flow output from the pump may be selectively controlled while balancing the loads in the pump, so that the mechanical torque/power required to the drive the pump may be reduced when one pumping chamber is ported to a lower path of resistance.

SUMMARY OF THE INVENTION

According to an exemplary embodiment of the present invention, there is provided a binary vane pump. The binary vane pump includes a pressure plate having a first discharge port and a second discharge port configured to discharge fluid from the binary vane pump to a first discharge path and a thrust plate having a third discharge port and a fourth discharge port configured to discharge fluid from the binary vane pump to a second discharge path. The binary vane pump further includes a ring positioned axially between the pressure plate and thrust plate, the ring having an inner cam surface, a rotor rotatably disposed within the ring, the rotor having a plurality of slots and a plurality of vanes, vanes of the plurality vanes corresponding to respective slots of the plurality of slots and radially movable with the respective slots, and a shaft extending along an axis through the rotor and configured to rotate the rotor so the vanes are rotatable within the ring.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a binary vane pump according to an exemplary embodiment of the present invention;

FIG. 2 is an exploded view of a binary vane pump according to an exemplary embodiment of the present invention;

FIG. 3 is an axial view of an inner side of a pressure plate of a binary vane pump according to an exemplary embodiment of the present invention;

FIG. 4 is an axial view of an inner side of a thrust plate of a binary vane pump according to an exemplary embodiment of the present invention; and

FIG. 5 is a diagram illustrating flow path through a binary vane pump according to an exemplary embodiment of the present invention;

DETAILED DESCRIPTION

Referring now to the Figures, where the invention will be described with reference to specific embodiments, without limiting same, FIGS. 1 and 2 show a binary vane pump 20 in accordance with an exemplary embodiment of the present invention. Referring to FIG. 1, the binary vane pump 20 includes a thrust plate 22, a ring 24, a rotor 26, a pressure plate 28 positioned about an axis ‘A’.

FIG. 2 shows an exploded view of the binary vane pump 20 according to an exemplary embodiment of the present invention. A shaft 30 extends through the thrust plate 22, ring 24, and rotor 26 along the axis ‘A’ and is configured to rotate to drive the binary vane pump 20. In an exemplary embodiment, the shaft 30 also extends at least partly into the pressure plate 28.

The thrust plate 22 includes a central opening 32, positioned about the axis ‘A’, through which the shaft 30 extends. The thrust plate 22 includes a flange configured so that the thrust plate 22 may be non-rotatably fastened to an adjacent vehicle component. Thus, the shaft 30 may rotate within the central opening 23 of the thrust plate 22.

In an exemplary embodiment, the ring 24 includes a plurality of intakes 34. In one example, the ring 24 may include four intakes 34. A first two intakes may be positioned on axially opposite sides of the ring 24. A second two intakes may be positioned on a diametrically opposite side of the ring 24 from the first two intakes, and may be positioned on axially opposite sides of the ring 24 from one another. It is understood, however, that a different number of intakes may be included, and the intakes may be positioned on adjacent components, such as the thrust plate 22 or the pressure plate 28.

An inner circumferential surface of the ring 24 presents an inner cam surface 36. The inner cam surface 36 defines a generally oblong or elongated shape such that ring 24 includes a generally oblong or elongated main chamber 38 radially bounded by the inner cam surface 36. The main chamber 38 has a minor diameter and a major diameter.

The rotor 26 is positioned in the main chamber 38 of the ring 24. The rotor 26 includes an opening 40 configured to receive the shaft 30. The shaft 30 is rotatable and the rotor 26 is connected to the shaft 30 at the opening 40 so that the rotor 26 rotates with the shaft 30. Thus, the rotor 26 may rotate about the axis ‘A’ together with the shaft 30. In an exemplary embodiment, the rotor 26 is positioned on a splined section of the shaft 30, and the rotor 26 includes a plurality of splines within the opening 40 to rotationally secure the rotor 26 to the shaft 30. It is understood, however, that other mechanisms may be used to rotationally secure the rotor 26 to the shaft 30 such that the rotor 26 rotates with the shaft 30.

The rotor 26 includes a plurality of radially extending slots 42 configured to receive respective vanes 44. The vanes 44 are movable in a radial direction of the rotor 26 within respective slots 42 so that the vanes 44 may contact the inner cam surface 36 during rotation of the rotor 26.

The rotor 26 is positioned within the main chamber 38 such that a variable clearance is formed between the rotor 26 and inner cam surface 36. The vanes 44 extend across the variable clearance and are movable with respect slots 42 to accommodate variances in the clearance. In an exemplary embodiment, the variable clearance is at a minimum value along the minor diameter. The variable clearance increases toward the major diameter and is at a maximum along the major diameter. The variable clearance decreases moving from the major diameter toward to the minor diameter.

The rotor 26 and the vanes 44 divide the main chamber 38 into a first pumping chamber 46 and a second pumping chamber 48 at the minor diameter. That is, the first pumping chamber 46 is formed on one side of the minor diameter and the second pumping chamber 48 is formed on another side of the minor diameter, separated from the first pumping chamber 46 by the rotor 26 and vanes 44. Accordingly, in an exemplary embodiment, the first pumping chamber 46 is positioned diametrically opposite from the second pumping chamber 48 in the ring 24. In an exemplary embodiment, a pumping chamber refers to a volume between the rotor 26 and the inner cam surface 36 of the ring 24 which includes at least one intake 34 and at least one discharge port in communication therewith, as described further below. In an exemplary embodiment, the thrust plate 22 and pressure plate 28 provide axial boundaries of the first pumping chamber 46 and second pumping chamber 48.

FIG. 3 illustrates an inner side of the pressure plate 28 according to an exemplary embodiment of the present invention. Referring to FIGS. 2 and 3, the pressure plate 28 includes an opening 50 centered on the axis ‘A’. The shaft 30 may extend through the opening 50. The inner side of the pressure plate 28 faces the ring 24, main chamber 38, first pumping chamber 46, second pumping chamber 48, rotor 26 and vanes 44. The pressure plate 28 is substantially rotationally fixed relative to the ring 24 and serves as an axial boundary for the first and second pumping chambers 46, 48 (FIG. 2). A high system pressure is applied on an outer surface of the pressure plate 28 to compress the pressure plate 28 and ring 24 together to minimize leakage paths.

In an exemplary embodiment, the pressure plate 28 includes a first discharge port 52 and a second discharge port 54. The first discharge port 52 is in fluid communication with the first pumping chamber 46 and discharges to a first discharge path 56 outside of the first pumping chamber 46. The second discharge port 54 is in fluid communication with the second pumping chamber 48 and also discharges to the first discharge path 56 outside of the second pumping chamber 48. Thus, the first and second discharge ports 52, 54 allow fluid to flow from the first pumping chamber 46 and second pumping chamber 48 to the first discharge path 56. The first discharge path 56 flows to a hydraulic load downstream from the binary vane pump 20. A high system pressure from the hydraulic load acts against the binary vane pump 20 in via the first discharge path 56.

In an exemplary embodiment, the first and second discharge ports 52, 54 may be formed as openings extending axially through an axial face of the pressure plate 28. However, it is understood the present invention is not limited to this example, and that other configurations of the first and second discharge ports 52, 54 are envisioned. For example, the first and second discharge ports 52, 54 may extend radially through a radial wall or extend through a combination of an axial wall and radial wall.

FIG. 4 illustrates an inner side of the thrust plate 22 according to an exemplary embodiment of the present invention. In an exemplary embodiment, the thrust plate 22 includes a third discharge port 58 and a fourth discharge port 60. The third discharge port 58 is in fluid communication with the first pumping chamber 46 and discharges to a second discharge path 62 outside of the first pumping chamber 46. The fourth discharge port 60 is in fluid communication with the second pumping chamber 48 and discharges to the second discharge path 62 outside of the second pumping chamber 48. In the exemplary embodiments above, the third and fourth discharge ports 58, 60 allow fluid to flow from the first pump chamber 46 and second pump chamber 48 to the second discharge path 62.

In an exemplary embodiment, the third and fourth discharge ports 58, 60 may both include an inlet 64 formed in an axial face of the thrust plate 22 and extend partially through the thrust plate 22 to an outlet 66 formed in an outer radial wall of the thrust plate 22. Thus, fluid flowing from the first and second pumping chambers 46, 48 may flow through respective inlets 64 of the third and fourth discharge ports 58, 60 formed on an axial face, and be discharged from the thrust plate through respective outlets 66 on an outer radial wall. It is understood the present invention is not limited to this example, and that other configurations of the third and fourth discharge ports 58, 60 are envisioned. For example, the third and fourth discharge ports 58, 60 may extend axially through an axial wall, or radially through a radial wall.

In an exemplary embodiment, the first discharge port 52 and the second discharge port 54 are positioned diametrically opposite, i.e., 180 degrees apart, from one another on the pressure plate 28. In addition, the third discharge port 58 and the fourth discharge port 60 are positioned diametrically opposite, i.e., 180 degrees apart, from one another on the thrust plate 22. Due to this positioning of the discharge ports, fluid discharge loads on the pump 20 may be balanced, and stresses on various pump components may be minimized. It is understood however that the present invention is not limited to this specific configuration. For example, the first and second discharge ports 52, 54 may be positioned at non-180 degree angles relative to one another, so long as fluid discharge loads, and in turn, stresses on the pump are maintained at a suitable level. Likewise, the third and fourth discharge ports 58, 60 may also be positioned at non-180 degree angles relative to one another.

While the first and second discharge ports 52, 54 are described as being positioned in the pressure plate 28 and the third and fourth discharge ports 58, 60 are described as being positioned in the thrust plate 22 in the exemplary embodiments above, it is understood that the first, second, third and fourth discharge ports 52, 54, 58, 60 may all be positioned either the pressure plate 28 or the thrust plate, or some combination thereof.

In an exemplary embodiment, the first and second discharge ports 52, 54 are formed of a similar size, shape and configuration, as each other so that similar quantities of fluid may flow therethrough. Accordingly, a balanced fluid discharge load may be achieved. Likewise, the third and fourth discharge ports 58, 60 may be formed similarly as well.

A pumping volume is defined between two adjacent vanes 44, the rotor 26, the inner cam surface 36, the thrust plate 22 and the pressure plate 28. In operation, the pumping volume increases as adjacent vanes 44 rotate from the minor diameter toward the major diameter. The pumping volume becomes at least partially filled with the fluid during rotation. The pumping volume then decreases as the rotor 26 rotates and the adjacent vanes 44 move from the major diameter toward the minor diameter. The decrease in pumping volume causes an increase in pressure on the fluid. The increased pressure causes the fluid to flow from the pumping volume out through a discharge port 52, 54, 58, 60. For example, the first discharge port 52 is positioned in fluid communication with the first pumping chamber 46 at a location where pressure within the pumping volume is sufficient to force the fluid to flow from the first pumping chamber 46 through the first discharge port 52 to the first discharge path 56. Likewise, the second discharge port 54 is positioned in fluid communication with the second pumping chamber 48 at a location where pressure within the pumping volume is sufficient to force the fluid to flow from the second pumping chamber 48 through the second discharge port 54 to the first discharge path 56.

Referring again to FIG. 3, the inner side of the pressure plate 28 may further include at least one first undervane port 57. In an exemplary embodiment, the first undervane port 57 may be formed as an opening extending through the pressure plate 28. The first undervane port 57 is configured to communicate the high system pressure applied on an outer or back surface of the pressure plate 28 to the vanes 44 as a first undervane pressure, to urge the vanes 44 radially outward from the rotor 26 and into contact with the inner cam surface 36. That is, high system pressure from outside the main chamber 38 may be exerted on the vanes 44 as an undervane pressure to act behind the vanes (i.e., on a radially inner side) and urge the vanes 44 into contact with the inner cam surface 36 in one of, or both of the first pumping chamber 46 and second pumping chamber 48. The vanes 44 may also be urged into contact with the inner cam surface 36 due a centripetal force resulting from rotation of the rotor 26. The first undervane port, or ports, 57 may be in fluid communication with a respective first and/or second discharge port 52, 54. For example, a channel may extend along the inner axial surface of the pressure plate from the undervane port 57 to the respective discharge port 52, 54.

Referring again to FIG. 4, the inner side of the thrust plate 22 may include at least one second undervane port 68. In an exemplary embodiment, the second undervane port 68 may be formed as an opening extending through the thrust plate 22. The second undervane port 68 is configured to communicate high system pressure to the vanes 44 as a second undervane pressure, to urge the vanes 44 radially outward from the rotor 26 and into contact with the inner cam surface 36. As noted above, the vanes 44 may also be urged into contact with the inner cam surface 36 due a centripetal force resulting from rotation of the rotor 26. The second undervane port, or ports, 68 may be in fluid communication with a respective third and/or fourth discharge port 58, 60. For example, a channel may extend along the inner axial surface of the thrust plate 22 from the second undervane port 68 to the respective discharge port 58, 60. The channel may also be formed within the thrust plate 22 itself, so that the channel is not open to directly to a pumping chamber 46, 48.

It is understood that the undervane ports 57, 68 are not limited to the configurations described above. For example, the undervane ports may be formed on only one of the pressure plate 28 and thrust plate 22.

FIG. 5 is a diagram of a flow path through a binary vane pump 20 according to an exemplary embodiment of the present invention. The first and second discharge ports 52, 54 are fluidly coupled to and discharge fluid to the first discharge path 56. The first discharge path 56 acts on a high system pressure to drive a hydraulic load H.

The third and fourth discharge ports 58, 60 are fluidly coupled to and discharge fluid to the second discharge path 62. The second discharge path 62 is selectively separated from the first discharge path 56 by a check valve 70 positioned in the second discharge path 62. With the check valve 70 in a closed position, the second discharge path 62 is isolated from the high system pressure and hydraulic load H. Thus, the binary vane pump 20 does not require an increased amount of force to pump the fluid against the high system pressure out of the third and fourth and discharge ports 58, 60. When the check valve 70 is closed, a reservoir valve is opened so that fluid from the second discharge path 62 may flow to the low pressure reservoir 72 fluidly coupled to the second discharge path. That is, the pump 20 pumps against a low pressure rather than a high pressure through the third and fourth discharge ports 58, 60 when the check valve 70 is closed, thereby requiring less power/torque.

In operation, the binary vane pump 20 may operate to provide a stepwise variable displace to account for “high load” and “low load” scenarios. In a high load scenario, the check valve 70 is controlled to move to an open position and the reservoir valve is closed. With the check valve 70 in the open position, both the first discharge path 56 and second discharge path 62 are exposed to the high system pressure. Thus, in the high load scenario, the binary vane pump 20 pumps fluid through the first and second discharge ports 52, 54 into the first discharge path 56 and through the third and fourth discharge ports 58, 60 into the second discharge path 62 to act against the hydraulic load H. Accordingly, in the high load scenario, the binary vane pump 20 has an increased fluid output to the hydraulic load.

In the low load scenario, the check valve 70 is moved to a closed position, thereby restricting flow from the second discharge path 62 to the hydraulic load and the reservoir valve is opened. Thus, in this scenario, only fluid discharged through the first and second discharge ports 52, 54 acts against the hydraulic load. The second discharge path 62 is connected to a lower pressure reservoir 72. Thus, the pump 20 is pumping against a low resistance through the third and fourth discharge ports 58, 60. Accordingly, the binary vane pump 20 requires less power to operate.

It is understood that addition discharge ports may be provided in the pressure plate and/or thrust plate which have a check valve positioned between them and the hydraulic load, such that additional load may be output from the pump 20 upon opening of the check valve, and the output of the pump 20 maybe more accurately controlled.

With further reference to FIG. 5, the binary vane pump 20 may also include a series of grooves and sealing devices installed in the grooves along an outer periphery. In an exemplary embodiment, the thrust plate 22 may include two circumferential grooves 74, with an O-ring 76 positioned in each groove. Further, the pressure plate 28 may include a groove 78 having an O-ring 80 positioned therein.

The integration of the features above may be utilized to effectively achieve better control over flow and pressure, and thus, provide a more efficient use of mechanical torque/power. In addition, the configurations described in the exemplary embodiments above may provide a balanced output from the binary vane pump, which may reduces stresses within the pump and surrounding components. The binary vane pump 20 of the exemplary embodiments above may be used together with, for example, an automatic transmission system to power or lubricate the system, or engine oil pumps. It is understood that the binary vane pump 20 of the exemplary embodiments above may be used together with other hydraulic systems as well, and in particular, hydraulic systems where it may be advantageous to selectively control the flow from the pump.

In the exemplary embodiments above, the first and second pumping chambers 46, 48 discharge fluid primarily through the first and second discharge ports 52, 54 to work against high system pressure in a low load scenario. Where higher output is required from the pump 20 to act against a higher hydraulic load, the check valve 70 may be opened, while the reservoir valve is closed. Accordingly, the first and second pumping chambers 46, 48 discharge fluid through the first and second discharge ports 52, 54 and the third and fourth discharge ports 58, 60 to work against the high system pressure from the hydraulic load H. In addition, because the first and second discharge ports may be positioned diametrically opposite from another, and the third and fourth discharge ports may be positioned diametrically opposite one another, output from the pump is balanced and stresses resulting from imbalanced discharge may be reduced or eliminated.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description. 

Having thus described the invention, it is claimed:
 1. A binary vane pump comprising: a pressure plate including a first discharge port and a second discharge port configured to discharge fluid from the binary vane pump to a first discharge path; a thrust plate including a third discharge port and a fourth discharge port configured to discharge fluid from the binary vane pump to a second discharge path; a ring positioned axially between the pressure plate and thrust plate, the ring having an inner cam surface; a rotor rotatably disposed within the ring, the rotor comprising a plurality of slots and a plurality of vanes, vanes of the plurality vanes corresponding to respective slots of the plurality of slots and radially movable with the respective slots; and a shaft extending along an axis through the rotor and configured to rotate the rotor so the vanes are rotatable within the ring.
 2. The binary vane pump of claim 1, wherein the ring defines an elongated main chamber having a minor diameter and a major diameter.
 3. The binary vane pump of claim 2, wherein the rotor and vanes are positioned within the ring to divide the main chamber into a first pumping chamber at one side of the minor axis and a second pumping chamber at another side of the minor axis.
 4. The binary vane pump of claim 3, wherein the first discharge port and third discharge port are in fluid communication with the first pumping chamber and the second discharge port and fourth discharge port are in fluid communication with the second pumping chamber.
 5. The binary vane pump of claim 4, wherein the first discharge port and second discharge port are positioned diametrically opposite to one another.
 6. The binary vane pump of claim 5, wherein the third discharge port and fourth discharge port are positioned diametrically opposite to one another.
 7. The binary vane pump of claim 6, wherein the second discharge path is selectively separated from the first discharge path by a check valve.
 8. The binary vane pump of claim 7, wherein the second discharge path is in fluid communication with a low pressure reservoir when the second discharge path is separated from the first discharge path by the check valve.
 9. The binary vane pump of claim 1, wherein the pressure plate further comprises at least one first undervane port configured to supply a first undervane pressure.
 10. The binary vane pump of claim 9, wherein the first undervane pressure urges the plurality of vanes into contact with the inner cam surface.
 11. The binary vane pump of claim 10, wherein the thrust plate further comprises at least one second undervane port configured to supply a second undervane pressure.
 12. The binary vane pump of claim 11, wherein the second undervane pressure urges the plurality of vanes into contact with the inner cam surface.
 13. The binary vane pump of claim 1, wherein the thrust plate further comprises at least one second undervane port configured to supply a second undervane pressure.
 14. The binary vane pump of claim 13, wherein the second undervane pressure urges the plurality of vanes into contact with the inner cam surface. 